Heat spreader with vapor chamber and heat dissipation apparatus using the same

ABSTRACT

A heat dissipation apparatus includes a heat sink ( 30 ) and a heat spreader ( 10 ). The heat spreader includes a heating area ( 11 ) and a cooling area ( 13 ), and defines a vapor chamber ( 16 ) therein. A plurality of artery meshes ( 151 ) are arranged in the vapor chamber and extend from the heating area towards the cooling area. A working medium is contained in the artery meshes. The artery meshes are located between wick structures ( 15   a   , 15   b ) attached to a top cover ( 14 ) and a base plate ( 12 ) of the heat spreader, respectively, and contact therewith.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to heat spreaders, and more particularly to a heat spreader having a vapor chamber for transfer or dissipation of heat from a heat-generating component and a heat dissipation apparatus using the same.

2. Description of Related Art

Nowadays, heat spreaders are used in electronic products for dissipating heat generated by electronic components such as CPUs. Typically, the heat spreader includes a vacuum vessel defining therein a vapor chamber, a wick structure provided in the chamber and lining an inside wall of the vessel, and a working fluid contained in the wick structure. The heat spreader is arranged to have an intimate contact with the electronic component so as to form a heating area at a middle portion of the heat spreader corresponding to the electronic component and a cooling area at the other portion of the heat spreader.

As the electronic component is maintained in thermal contact with the heat spreader, the working fluid contained in the wick structure corresponding to the heating area vaporizes. The vapor then spreads to fill the chamber, and wherever the vapor comes into contact with the cooling area of the vessel, it releases its latent heat of vaporization and condenses. The condensate returns to the heating area via a capillary force generated by the wick structure. Thereafter, the condensate frequently vaporizes and condenses to thereby remove the heat generated by the electronic component.

As progress continues to be made in electronics area, the electronic components are made to be more powerful while occupying a smaller size. Thus, the heating area needs to transfer more heat to the cooling area of the heat spreader. In contrast, the heating area of the heat spreader is decreased as the size of the electronic component is decreased, and the cooling area of the heat spreader is commensurately increased. Therefore, the heat flux density between the heating and the cooling areas of the heat spreader is increased. Accordingly, the wick structure needs to have more powerful heat transfer capability. However, the wick structure of the heat spreader selected from the conventional types, such as mesh, fiber, fine grooves, and sintered powder, cannot satisfy such requirement, which further limits the increase for the heat transfer capability of the heat spreader. Therefore, it is need to provide a heat spreader which contains a wick structure having more powerful heat transfer capability.

SUMMARY OF THE INVENTION

The present invention relates, in one aspect, to a heat spreader for transfer or dissipation of heat from a heat-generating component and a heat dissipation apparatus using the same. The heat dissipation apparatus includes a heat sink and a heat spreader. The heat spreader includes a heating area and a cooling area, and defines a vapor chamber therein. A plurality of artery meshes are arranged in the vapor chamber and extend from the heating area outwardly towards the cooling area. Wick structures are respectively attached to a top surface of a base plate and a bottom surface of a top cover of the heat spreader. The artery meshes are sandwiched between the wick structures. A working medium is contained in the artery meshes and the wick structures. In addition to be transferred vertically upwardly to reach a heat sink on the heat spreader by vaporization of the working medium, heat absorbed by the heating area of the heat spreader can be transferred to the cooling area horizontally via the artery meshes.

Other advantages and novel features of the present invention will become more apparent from the following detailed description of preferred embodiments when taken in conjunction with the accompanying drawings, in which:

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view of a heat dissipation apparatus in accordance with a preferred embodiment of the present invention;

FIG. 2 is a cross-sectional view of a heat spreader of FIG. 1;

FIG. 3 is a top, cross-sectional view of the heat spreader of FIG. 2, taken along line III-III thereof;

FIG. 4 is a partly enlarged view of an artery mesh of the heat spreader of FIG. 3, in circle IV; and

FIG. 5 is an enlarged transverse view of the artery mesh of FIG. 4, taken along line V-V thereof.

DETAILED DESCRIPTION OF THE INVENTION

Referring to FIG. 1, a heat dissipation apparatus in accordance with a preferred embodiment of the present invention is shown. The heat dissipation apparatus is mounted on a heat generating electronic component 20 such as a CPU (central processing unit), a North Bridge chip, a GPU (graphic processing unit) of a VGA card (video graphics array card) or an LED (light emitting diode). The heat dissipation apparatus includes a heat spreader 10 and a heat sink 30 mounted on the heat spreader 10.

The heat sink 30 is made of materials having high thermal conductive capabilities such as copper or aluminum. The heat sink 30 includes a rectangular shaped bottom base 31 and a plurality of fins 32 perpendicularly and upwardly extending from the bottom base 31. The bottom base 31 has an intimate contact with the heat spreader 10 so as to absorb heat therefrom. The fins 32 dissipate the heat absorbed from the heat spreader 10 to the surrounding environment.

Referring to FIGS. 2 and 3, the heat spreader 10 has a flat type configuration and is rectangular shaped when viewed from above. The heat spreader 10 includes a rectangular shaped base plate 12, a top cover 14 covering the base plate 12, and wick structures 15 disposed in a sealed vapor chamber 16 defined between the base plate 12 and the top cover 14. The base plate 12 and the top cover 14 are made of the materials having high thermal conductive capabilities, such as copper or aluminum. The top cover 14 includes a flat covering plate 141 parallel to the base plate 12, four sidewalls 142 perpendicularly and downwardly extending from a periphery of the covering plate 141, and four joint plates 140 horizontally extending from free ends of the sidewalls 142. A thickness of the heat spreader 10 is determined by a height of the sidewall 142 and thicknesses of the base plate 12 and the covering plate 141, and is preferably between about 2 and about 3.5 millimeters (mm). In this embodiment, the thickness of the heat spreader 10 is 3 mm. The joint plates 140 are welded to a periphery 120 of the base plate 12 so as to form the sealed vapor chamber 16 between the base plate 12 and the top cover 14. The vapor chamber 16 of the heat spreader 10 is evacuated to form a vacuum and a working medium is contained in the wick structures 15. The working medium can be selected from a liquid such as water, alcohol, or methanol, which has lower boiling point and is compatible with the wick structures 15. In this embodiment, the working medium is water.

The heat generating electronic component 20 is disposed under and has an intimate contact with a central portion of the base plate 12. A substantially rectangular shaped heating area 11 is formed at the central portion of the heat spreader 10, absorbing heat from the heat generating electronic component 20. A cooling area 13 is formed at the other portion of the heat spreader 10 and surrounds the heating area 11, transferring the heat to the heat sink 30 and dissipating the heat to the surrounding environment. That is, the cooling area 13 directly dissipates the heat to the surrounding environment at a bottom of the heat spreader 10, and transfers the heat to the heat sink 30 at a top thereof.

The wick structures 15 includes first and second wicks 15 a, 15 b respectively attached to the base plate 12 and the covering plate 141, and six artery meshes 151 sandwiched between the first and the second wicks 15 a, 15 b. The first and the second wicks 15 a, 15 b are selected from mesh, fiber, fine grooves, sintered powder, carbon nanotube arrays and composite of such wicks. The artery meshes 151 are symmetrically disposed at two opposite sides of the heating area 11. As viewed from above, the artery meshes 151 radially extend from the central portion (heating area 11) of the heat spreader 10 towards a periphery (corners of the cooling area 13) thereof. Two of the artery meshes 151 are arranged at a middle portion of heat spreader 10 and are in line with each other, and the other four artery meshes 151 extend from corners of the heating area 11 towards corners of the cooling area 13 of the heat spreader 10. That is, each of the artery mesh 151 has an inner end 1513 located at the heating area 11 of the heat spreader 10 and an outer end 1514 located at the cooling area 13 thereof. Therefore, the working medium can move horizontally between the heating and the cooling areas 11, 13 of the heat spreader 10 via capillary forces generated by the artery meshes 151.

Referring to FIGS. 4 and 5, the artery mesh 151 is a flexible elongate hollow tube which is woven from a plurality of metal wires such as copper wires, aluminum wires, or stainless steel wires. Alternatively, the artery mesh 151 can also be woven from a plurality of fiber wires. In this embodiment, the artery mesh 151 is woven from a plurality of copper wires. A diameter of the copper wire can be about 0.05 mm. A plurality of pores are defined in a wall 1512 of the artery mesh 151. The pores communicate the artery meshes 151 with the first and the second wicks 15 a, 15 b so that the working medium can move between top and bottom portions of the heat spreader 10. That is, the working medium can move between the first and the second wicks 15 a, 15 b via capillary forces generated by the artery meshes 151. The artery mesh 151 has an annular cross section and a channel 1510 is defined in a middle portion of the artery mesh 151. A diameter of the channel 1510 is preferably from 0.5 mm to 2 mm. The diameter of the channel 1510 is 1 mm in this embodiment. A diameter of an outer surface of the artery mesh 151 substantially equals a distance between the first and the second wicks 15 a, 15 b, so that the artery mesh 151 has intimate contact with the first and the second wicks 15 a, 15 b. A thickness of the wall 1512 of the artery mesh 151 is determined by the amount and the diameter of the wires. In this embodiment, the thickness of the wall 1512 of the artery mesh 151 is about 0.2 mm.

In operation of the heat dissipation apparatus, the working fluid contained in the second wick 15 b corresponding to the heating area 11 vaporizes due to the heat absorbed from the heat generating electronic component 20. The vapor then spreads to fill the vapor chamber 16, and wherever the vapor comes into contact with the cooling area 13 of the heat spreader 10, it releases its latent heat of vaporization and condenses. The vapor moves vertically upwardly to transfer the heat to the heat sink 30. Furthermore, the vapor moves horizontally along the channels 1510 of the artery meshes 151 to transfer the heat to the cooling area 13 of the heat spreader 10. The heat is therefore directly dissipated to the surrounding environment at the bottom of the heat spreader 10 and evenly transferred to the heat sink 30 at the top thereof, which further dissipates the heat to the surrounding environment. The condensate returns to the heating area 11 due to the capillary forces generated by the artery meshes 151 and the first and the second wicks 15 a, 15 b. Thereafter, the condensate continues to vaporize and condense, thereby removing the heat generated by the heat generating electronic component 20.

In the present heat spreader 10, the artery mesh 151 helps the working medium at the cooling area 13 of the heat spreader 10 to move towards the heating area 11 thereof. That is, the artery mesh 151 helps the working medium to horizontally move in the heat spreader 10. This increases the heat transfer capability of the heat spreader 10. Furthermore, the artery mesh 151 also helps the working medium at the top portion of the heat spreader 10 to move towards the bottom portion thereof. That is, the artery mesh 151 helps the working medium to perpendicularly move in the heat spreader 10. This further increases the heat transfer capability of the heat spreader 10.

It is to be understood, however, that even though numerous characteristics and advantages of the present invention have been set forth in the foregoing description, together with details of the structure and function of the invention, the disclosure is illustrative only, and changes may be made in detail, especially in matters of shape, size, and arrangement of parts within the principles of the invention to the full extent indicated by the broad general meaning of the terms in which the appended claims are expressed. 

1. A heat spreader comprising: a base plate; a top cover hermetically covering the base plate; a vapor chamber defined between the base plate and the top cover; wick structures disposed in the vapor chamber; working medium contained in the wick structures, wherein the wick structures comprise first and second wicks respectively attached to a top face of the base plate and a bottom face of the top cover; and a plurality of artery meshes sandwiched between the first and the second wicks, the working medium being also contained in the plurality of artery meshes.
 2. The heat spreader as described in claim 1, wherein the plurality of artery meshes are symmetrically disposed in the vapor chamber.
 3. The heat spreader as described in claim 1, wherein the plurality of artery meshes comprise two artery meshes arranged at a middle portion of the heat spreader, and four artery meshes extending from a place near neighboring ends of the two artery meshes towards four corners of the heat spreader, respectively.
 4. The heat spreader as described in claim 1, wherein each of the plurality of artery meshes is a hollow tube, a channel being defined in a middle portion of the hollow tube and a plurality of pores being defined in a wall of the hollow tube.
 5. The heat spreader as described in claim 4, wherein a diameter of each of the plurality of artery meshes equals to a distance between the first and the second wicks.
 6. The heat spreader as described in claim 4, wherein a diameter of each of the plurality of artery meshes is in an approximate range from 0.5 mm to 2 mm.
 7. The heat spreader as described in claim 4, wherein each of the plurality of artery meshes is woven from a plurality of wires selected from copper wires, aluminum wires, stainless steel wires and fiber wires.
 8. The heat spreader as described in claim 7, wherein a diameter of the wire is 0.05 mm, a thickness of the wall of each of the plurality of artery meshes is 0.2 mm, and a diameter of the channel is 1 mm.
 9. The heat spreader as described in claim 1, wherein a thickness of the heat spreader is in an approximate range from 0.5 mm to 2 mm.
 10. The heat spreader as described in claim 1, wherein the first and second wicks are selected from mesh, fiber, fine grooves, sintered powder and carbon nanotube arrays.
 11. A heat dissipation apparatus comprising: a heat sink; and a heat spreader on which the heat sink is mounted, comprising a heating area and a cooling area surrounding the heating area, and defining a vapor chamber therein, a plurality of artery meshes being arranged in the vapor chamber and extending from the heating area outwardly towards the cooling area, wherein a working medium is contained in the plurality of artery meshes.
 12. The heat dissipation apparatus as described in claim 11, further comprising first and second wicks disposed at top and bottom portions of the heat spreader respectively, the plurality of artery meshes being sandwiched between the first and the second wicks.
 13. The heat dissipation apparatus as described in claim 12, wherein the first and second wicks are selected from mesh, fiber, fine grooves, sintered powder and carbon nanotube arrays.
 14. The heat dissipation apparatus as described in claim 11, wherein each of the plurality of artery meshes is a hollow tube woven from a plurality of wires selected from copper wires, aluminum wires, stainless steel wires and fiber wires, a channel being defined in a middle portion of the hollow tube and a plurality of pores being defined in a wall of the hollow tube.
 15. The heat dissipation apparatus as described in claim 14, wherein a diameter of the wire is 0.05 mm, a thickness of the sidewall of each of the plurality of artery meshes is 0.2 mm, and a diameter of the channel is 1 mm.
 16. The heat dissipation apparatus as described in claim 11, wherein a diameter of each of the plurality of artery meshes is in an approximate range from 0.5 mm to 2 mm.
 17. The heat dissipation apparatus as described in claim 1, wherein a thickness of the heat spreader is in an approximate range from 0.5 mm to 2 mm.
 18. The heat dissipation apparatus as described in claim 11, wherein the heat sink has a plurality of fins.
 19. A heat dissipation apparatus, comprising: a heat spreader having a base plate and a top cover hermetically connected to the base plate, wherein wick structures are attached to a top face of the base plate and a bottom face of the top cover, respectively, at least an artillery mesh being located between the wick structures, contacting therewith and extending from a place near a middle portion of the heat spreader outward toward an edge of the heat spreader, wherein the artillery mesh is in a form of a flexible elongate hollow tube which is woven from a plurality of wires; and a heat sink mounted on the top cover of the heat spreader and thermally connecting therewith. 